Mott-Hubbard quantum criticality in paramagnetic CMR pyrochlores

We present a correlated {\it ab initio} description of the paramagnetic phase of Tl$_2$Mn$_2$O$_7$, employing a combined local density approximation (LDA) with multiorbital dynamical mean field theory (DMFT) treatment. We show that the insulating state observed in this colossal magnetoresistance (CMR) pyrochlore is determined by strong Mn intra- and inter-orbital local electron-electron interactions. Hybridization effects are reinforced by the correlation-induced spectral weight transfer. Our result coincides with optical conductivity measurements, whose low energy features are remarkably accounted for by our theory. Based on this agreement, we study the disorder-driven insulator-metal transition of doped compounds, showing the proximity of Tl$_2$Mn$_2$O$_7$ to quantum phase transitions, in agreement with recent measurements.Comment: 4 pages, 4 figure

Kondo lattice model at half-filling

The single- and two-channel Kondo lattice model consisting of localized spins interacting antiferromagnetically with the itinerent electrons, are studied using dynamical mean field theory. As an impurity solver for the effective single impurity Anderson model we used the exact diagonalization (ED) method. Using ED allowed us to perform calculations for low temperatures and couplings of arbitrary large strength. Our results for the single-channel case confirm and extend the recent investigations. In the two-channel case we find a symmetry breaking phase transition with increasing coupling strength.Comment: 11 pages, 5 figure

A multi-methodological study of the (K,Ca)-variety of the zeolite merlinoite

A multi-methodological study of the (K,Ca)-variety of the zeolite merlinoite from Fosso Attici, Sacrofano, Italy was carried out on the basis of electron microprobe analysis in wavelength dispersive mode, singlecrystal X-ray diffraction (at 100 K), Raman and infrared spectroscopy. The chemical formula of the merlinoite from Fosso Attici is (Na0.37K5.69)\u3a3=6.06(Mg0.01Ca1.93Ba0.40)\u3a3=2.34(Fe3+0.02Al10.55Si21.38)\u3a3=31.9O64\u38719.6H2O, compatible with the ideal chemical formula K6Ca2[Al10Si22O64]\u38720H2O. Anisotropic structure refinements confirmed the symmetry and the framework model previously reported (space group Immm, a = 14.066(5),b = 14.111(5), c = 9.943(3) \uc5 at 100 K). Refinement converged with four cationic sites and sixH2Osites; refined bond distances of the framework tetrahedra suggest a highly disordered Si/ Al-distribution. The Raman spectrum of merlinoite (collected between 100 and 4000 cm 121) is dominated by a doublet of bands between 496\u2013422 cm 121, assigned to tetrahedral T\u2013O\u2013T symmetric bending modes. T\u2013O\u2013T antisymmetric stretching is also observed; stretching and bending modes of the H2O molecules are only clearly visiblewhen using a blue laser. The single-crystal near-infrared spectrum shows a very weak band at 6823 cm 121, assigned to the first overtone of the O\u2013H stretching mode, and a band at 5209 cm 121, due to the combination of H2O stretching and bendingmodes.Avery broad and convoluted absorption, extending from 3700 to 3000 cm 121 occurs in the H2O stretching region, while the \u3bd2 bending mode of H2O is found at 1649 cm 121. The powder midinfrared spectrum of merlinoite between 400\u20131300 cm 121 is dominated by tetrahedral T\u2013O\u2013T symmetric and antisymmetric stretches. Raman and Fourier-transform infrared spectroscopy spectra of merlinoite and phillipsite provide a quick identification tool for these zeolites, which are often confused due to their close similarity

On the Renormalizability of Noncommutative U(1) Gauge Theory - an Algebraic Approach

We investigate the quantum effects of the nonlocal gauge invariant operator $\frac{1}{{}{D}^{2}}{F}_{\mu \nu}\ast \frac{1}{{}{D}^{2}}{F}^{\mu \nu}$ in the noncommutative U(1) action and its consequences to the infrared sector of the theory. Nonlocal operators of such kind were proposed to solve the infrared problem of the noncommutative gauge theories evading the questions on the explicit breaking of the Lorentz invariance. More recently, a first step in the localization of this operator was accomplished by means of the introduction of an extra tensorial matter field, and the first loop analysis was carried out $(Eur.Phys.J.\textbf{C62}:433-443,2009)$. We will complete this localization avoiding the introduction of new degrees of freedom beyond those of the original action by using only BRST doublets. This will allow us to make a complete BRST algebraic study of the renormalizability of the theory, following Zwanziger's method of localization of nonlocal operators in QFT.Comment: standard Latex no figures, version2 accepted in J. Phys A: Math Theo

The interfruta project and its contribution to the knowledge of chestnut moth (Cydia splendana Hubner)(Lepidoptera: Tortricidae) dispersal and infestation on Terceira Island, Azores

The chestnut moth is one of the principal pests on Terceira Island affecting the quality of all chestnut production. Investigation work developed by the Interfruta II Project (a project of interregional cooperation among the three Atlantic regions: Azores, Madeira and Canaries) aims at increasing interest in fruit and the vineyard production in the three partner regions. The chestnut moth (Cydia splendana Hubner) (Lepidoptera: Tortricidae) is the only specie responsible for chestnut fruit damage. The monitoring of this pest using Delta traps with sex pheromone revealed the adult abundance during the season. The higher activity period was between July and October, the months when the chestnut harvest begins. A map of Terceira Island using a GPS and ArcGis 8.0 software was made showing the locality of all the chestnut production areas studied. In the evaluated orchards, fruit damage reached its maximum of 38% at Terra Chã, 218 m of altitude and a southern exposure, and a minimum of 0% damage at Biscoitos, at about the same altitude but with a northern exposure. In both cases, the percentages of infestation were achieved by analyzing a sample of 2.500 chestnuts for each parcel of land.info:eu-repo/semantics/publishedVersio

Healthcare workers and manual patient handling: A pilot study for interdisciplinary training

Manual patient handling (MPH) is a major occupational risk in healthcare settings. The aim of this study was to propose an MPH training model involving interdisciplinary aspects. A scheduled training program was performed with 60 healthcare workers (HCWs) from a hospital in Naples, Italy, providing training divided into three sections (occupational health—section one; physical therapy—section two; psychosocial section—section three) and lasting six hours. Fifty-two HCWs performed the training session. In section one, a questionnaire about risk perception related to specific working tasks was administered. Section two provided specific exercises for the postural discharge of the anatomical areas most involved in MPH. The last section provided teamwork consolidation through a role-playing exercise. The training program could also be useful for risk assessment itself, as they can examine the perceptions of the specific risk of the various workers and incorrect attitudes and therefore correct any incorrect procedures, reducing exposure to specific risks in the field. This pilot study proposes a training model that explores all aspects related to MPH risk exposure and also underlines the need for standardization of this formative model, which could represent a useful tool for studying the real effectiveness of training in workplaces

Assessing the potential of amino acid 13 patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis

Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing the biosynthetic origin of amino acid carbon skeletons, based on naturally occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions, and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results emphasize that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e., isoleucine, lysine, leucine and tyrosine), bacterially derived amino acids ranged from 10 to 15 % in the sediment layers from the last 5000 years, and up to 35 % during the last glacial period. The greater bacterial contributions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a function of sediment age, to a substantially larger degree than suggested by changes in total organic nitrogen and carbon content. It is uncertain whether archaea may have contributed to sedimentary δ13CAA patterns we observe, and controlled culturing studies will be needed to investigate whether δ13CAA patterns can differentiate bacterial from archeal sources. Further research efforts are also needed to understand how closely δ13CAA patterns derived from hydrolyzable amino acids represent total sedimentary proteineincous material, and more broadly sedimentary organic nitrogen. Overall, however, both our culturing and sediment studies suggest that δ13CAA patterns in sediments will represent a novel proxy for understanding both primary production sources, and the direct bacterial role in the ultimate preservation of sedimentary organic matter

Tolcapone, a potent aggregation inhibitor for the treatment of familial leptomeningeal amyloidosis

Hereditary transthyretin amyloidosis (ATTR) is a disease characterized by the extracellular deposition of transthyretin (TTR) amyloid fibrils. Highly destabilizing TTR mutations cause leptomeningeal amyloidosis, a rare, but fatal, disorder in which TTR aggregates in the brain. The disease remains intractable, since liver transplantation, the reference therapy for systemic ATTR, does not stop mutant TTR production in the brain. In addition, despite current pharmacological strategies have shown to be effective against in vivo TTR aggregation by stabilizing the tetramer native structure and precluding its dissociation, they display low brain permeability. Recently, we have repurposed tolcapone as a molecule to treat systemic ATTR. Crystal structures and biophysical analysis converge to demonstrate that tolcapone binds with high affinity and specificity to three unstable leptomeningeal TTR variants, stabilizing them and, consequently, inhibiting their aggregation. Because tolcapone is an FDA-approved drug that crosses the blood-brain barrier, our results suggest that it can translate into a first disease-modifying therapy for leptomeningeal amyloidosis. Databases PDB codes for A25T-TTR, V30G-TTR, and Y114C-TTR bound to tolcapone are 6TXV, 6TXW, and 6XTK, respectively

Magnetic control of large room-temperature polarization

Numerous authors have referred to room-temperature magnetic switching of large electric polarizations as The Holy Grail of magnetoelectricity.We report this long-sought effect using a new physical process of coupling between magnetic and ferroelectric relaxor nano-regions. Here we report magnetic switching between the normal ferroelectric state and the ferroelectric relaxor state. This gives both a new room-temperature, single-phase, multiferroic magnetoelectric, PbZr0.46Ti0.34Fe0.13W0.07O3, with polarization, loss (<4%), and resistivity (typically 108 -109 ohm.cm) equal to or superior to BiFeO3, and also a new and very large magnetoelectric effect: switching not from +Pr to negative Pr with applied H, but from Pr to zero with applied H of less than a Tesla. This switching of the polarization occurs not because of a conventional magnetically induced phase transition, but because of dynamic effects: Increasing H lengthens the relaxation time by x500 from 100 ?s, and it couples strongly the polarization relaxation and spin relaxations. The diverging polarization relaxation time accurately fits a modified Vogel-Fulcher Equation in which the freezing temperature Tf is replaced by a critical freezing field Hf that is 0.92 positive/negative 0.07 Tesla. This field dependence and the critical field Hc are derived analytically from the spherical random bond random field (SRBRF) model with no adjustable parameters and an E2H2 coupling. This device permits 3-state logic (+Pr,0,negative Pr) and a condenser with >5000% magnetic field change in its capacitance.Comment: 20 pages, 5 figure

Mediterranean spotted fever and encephalitis: a case report and review of the literature

Mediterranean spotted fever (MSF) is a disease caused by Rickettsia conorii and transmitted by the brown dog tick Rhipicephalus sanguineus. It is widely distributed through southern Europe, Africa, and the Middle East. It is an emerging or a reemerging disease in some regions. Countries of the Mediterranean basin, such as Portugal, have noticed an increased incidence of MSF over the past 10 years. It was believed that MSF was a benign disease associated with a mortality rate of 1-3% before the antimicrobial drug era. It was called benign summer typhus. Severe forms were described in 1981, and the mortality rate reached 32% in Portugal in 1997. However, neurological manifestations associated with brain lesions are a rare event. We describe the case of a man with fever, maculopapular rash, a black spot, and hemisensory loss including the face on the left side of the body with brain lesions in the imaging studies